1. Statement of the Technical Field
The inventive arrangements relate to communication systems and methods for call transfer. More particularly, the invention concerns systems and methods for patching full duplex calls into half-duplex calls.
2. Description of the Related Art
The Federal Communications Commission (“FCC”) has reserved twenty Mega Hertz of spectrum exclusively for the use of public safety in the United States. In this regard, the FCC set up a FirstNet Board to manage that spectrum and build out of the network that will be using that spectrum. The network employs a Long Term Evolution (“LTE”) technology for wireless communication of high-speed data between mobile devices. The LTE technology is well known in the art, and therefore will not be described in detail herein. However, it should be understood that the LTE technology supports packet switching within an Internet Protocol (“IP”) network.
The FirstNet Board has indicated a strong desire to enable end user services using all standards based solutions. The standards based solutions include, but are not limited to, an IP Multimedia Subsystem (“IMS”) based standard solution created by the 3rd Generation Partnership Project (“3GPP”). IMS is an architectural framework for delivering IP multimedia services, and therefore comprises a core network for a variety of standardized application layer services. The standardized application layer services include, but are not limited to, telephony services and group Push-To-Talk (“PTT”) services.
One such telephony service is referred to in the art as a Voice over LTE (“VoLTE”) service. The VoLTE service is an approach based on the IMS architectural framework, with specific profiles for control and media planes of voice services on LTE defined by the GSM Association (“GSMA”). In this regard, the VoLTE service allows users to establish person-to-person voice calls and video chats over an LTE core network using their cellular phones. Notably, these cellular phones need to have software loaded thereon to provide the VoLTE functionality. This functionality would typically be integrated with the cellular phones according to the requirements of a service provider prior to the cellular phones being sold to users.
The PTT service has been standardized by the Open Mobile Alliance (“OMA”). The PTT service could be provided by an app or in an integrated solution according to the requirements of the service provider. The PTT service provides a way to have conversations on half-duplex communication lines, including two-way radio, using a single button to switch between transmit mode and receive mode. The PTT service for a cellular phone network is known in the art as Push to Talk over Cellular (“PoC”). PoC is a service option for the cellular phone network which permits subscribers to use their phone as a walkie-talkie with a range limited to the coverage area of the cellular network. A significant advantage of the PoC is the ability for a single user to reach many users on an active talk group with a single button press. The user need not make several telephone calls to coordinate with the members of the active talk group.
Notably, the VoLTE service and the PTT service are two separate services. Accordingly during operation of a communications device, a user can be concurrently engaged in a VoLTE person-to-person voice call and a PTT group call. For example, a first responder is engaged in a telephony call with a subject matter expert about hazardous material because a tanker has overturned on a highway, while concurrently being engaged in a PTT group call with all other first responders. The subject matter expert may have information that is pertinent to the entire group of first responders. Therefore, it is beneficial to have the subject matter expert convey such information directly to all of the first responders, rather than just one first responder. However, in some scenarios, the communications device of the subject matter expert may not have (1) the PTT group call functionality, (2) the group privileges, and/or (3) the required Quality of Service (“QoS”). Various solutions exist for addressing these scenarios such that the pertinent information can be conveyed from the expert to all of the first responders despite the absence of (1)-(3). All of these existing solutions are cumbersome and time consuming non-broadband solutions because they require: (a) a manual termination of the VoLTE call between the first responder and expert; and (b) a manual establishment of a new call between the expert and the first responder group. The new call is manually established by the expert using the user interface of the respective communication device. In this regard, the expert dials a new phone number and enters a talkgroup identifier when prompted. Once can appreciate that these existing solutions are undesirable in emergency situations where time if of the essence.